Putting the kettle on – all in the name of science

What can teabags tell us about how forest management and the changing environment affect our soil?

An innovative science experiment is underway that makes use of an everyday item familiar to most of us – the humble teabag. While we Brits go through vast numbers of them, this work isn’t limited to our nation of tea drinkers and forms part of a World Soil Carbon Decomposition Study. The project aims to create a world soil map of carbon decomposition to compare the effects of environmental changes on soil carbon decomposition rates globally. Forest management impacts and the influence of forest biodiversity on soil carbon dynamics will also be assessed.

Where do teabags come in?

Decomposition is an important process for life on earth and global change as it produces the greenhouse gas carbon dioxide (CO2). Teabags can help us to measure decomposition rates by seeing how well they decompose in a given timeframe.

The study, led by Umea University and Utrecht University, uses two specific types of teabags – green tea and rooibos. As they are composed of different material, the two types of tea have contrasting decomposition rates (green tea is fast and rooibos is slow).

The method is simple: we weigh the teabags before burying them in separate holes in the ground. After three months, we’ll dig them up and weigh them again. Through this process, Forest Research will provide soil decomposition data for more than 150 forest sites in the UK (some from the Level II and BioSoil networks, plus some experimental sites).

This is an innovative and cost-effective method to gather comparable data on decomposition rate using commercially available teabags.

Results in 2017

Our researchers buried the teabags in over half of our plots during the summer and are now digging them back up this autumn. The rest of the plots will have their teabags buried over three months in summer 2017. The results of this project will allow us to construct a decomposition curve and determine what is known as the ‘Teabag Index’ (TBI), which will allow us to compare decomposition rates in plots across the UK.

Not only will Forest Research be able to contribute to the results from this worldwide study, but we will also use the UK data for our own investigations into soil carbon decomposition related to soil type, geology, forest type, management, climate and pollution deposition.